1. Data are presented comprising the first quantitative survey lice from Neotropical birds. The data were collected in the Andean foothills of south-eastern Peru using a novel scheme for quantitative sampling of ectoparasites from freshly killed hosts. 2. In total, 685 birds representing 127 species in 26 families were sampled for lice; 327 (47.7\%) birds were parasitized, with a mean intensity of 6.6 lice per bird and a mean richness of 1.1 louse species per host species. 3. The bulk of variation in louse load was among host species nested within genera, although some variation occurred at higher taxonomic levels. 4. Lice were extremely host-specific; nearly all species were restricted to a single species of host (monoxenous). 5. Thirteen metapopulations of lice (10\%) had significantly skewed sex ratios, of which four were skewed toward males, representing the first male-biased sex ratios reported for chewing lice. Thirty-four metapopulations (27\%) had significantly skewed age ratios and showed an overall bias toward adults. 6. Results are discussed in relation to current life-history theory and are compared with the findings of a recent survey of lice from temperate-zone birds. Tropical lice are neither more speciose nor more abundant than temperate-zone lice, which is consistent with the view that the environment for chewing lice is delimited by the body of the host rather than by \&$\#$39;external\&$\#$39; conditions. 7. Non-quantitative host-parasite records are reported for lice collected from an additional 75 birds representing 45 species in 20 families.